Oracle Database Errors or Warnings from Error ORA-12511 to ORA-12522

ORA-12511: TNS:service handler found but it is not accepting connections
Cause: The dispatchers notified the listener that they temporarily do not accept new connections.
Action: Attempt the connection again. If error persists, contact the DBA to check the state of the dispatchers and/or ask him to increase the number of dispatchers.ORA-12513: TNS:service handler found but it has registered for a different protocol
Cause: The dispatchers registered for this service are connected to the listener by way of a different network protocol than that of the client.
Action: Contact the DBA to register a dispatcher on your protocol.ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
Cause: The listener received a request to establish a connection to a database or other service. The connect descriptor received by the listener specified a service name for a service (usually a database service) that either has not yet dynamically registered with the listener or has not been statically configured for the listener. This may be a temporary condition such as after the listener has started, but before the database instance has registered with the listener.
Action:
– Wait a moment and try to connect a second time.

– Check which services are currently known by the listener by executing: lsnrctl services <listener name>

– Check that the SERVICE_NAME parameter in the connect descriptor of the net service name used specifies a service known by the listener.

– If an easy connect naming connect identifier was used, check that the service name specified is a service known by the listener.

– Check for an event in the listener.log file.ORA-12515: TNS:listener could not find a handler for this presentation
Cause: None of the listener’s known service handlers are registered as supporting the presentation protocol required by the connecting client.
Action: Check that the destination service is configured to accept the presentation protocol.ORA-12516: TNS:listener could not find available handler with matching protocol stack
Cause: None of the known and available service handlers for the given SERVICE_NAME support the client’s protocol stack: transport, session, and presentation protocols.
Action: Check to make sure that the service handlers (e.g. dispatchers) for the given SERVICE_NAME are registered with the listener, are accepting connections, and that they are properly configured to support the desired protocols.ORA-12518: TNS:listener could not hand off client connection
Cause: The process of handing off a client connection to another process failed.
Action: Turn on listener tracing and re-execute the operation. Verify that the listener and database instance are properly configured for direct handoff. If problem persists, call Oracle Support.

ORA-12519: TNS:no appropriate service handler found
Cause: The listener could not find any available service handlers that are appropriate for the client connection.
Action: Run “lsnrctl services” to ensure that the instance(s) have registered with the listener, and are accepting connections.ORA-12520: TNS:listener could not find available handler for requested type of server
Cause: None of the known and available service handlers for requested type of server (dedicated or shared) are appropriate for the client connection.
Action: Run “lsnrctl services” to ensure that the instance(s) have registered with the listener and that the appropriate handlers are accepting connections.ORA-12521: TNS:listener does not currently know of instance requested in connect descriptor
Cause: The listener received a request to establish a connection to a database or other service. The connect descriptor received by the listener specified in addition to the service name an instance name for an instance (usually a database instance) that either has not yet dynamically registered with the listener or has not been statically configured for the listener. This may be a temporary condition such as after the listener has started, but before the database instance has registered with the listener.
Action:
– Wait a moment and try to connect a second time.

– Check which instances are currently known by the listener by executing: lsnrctl services <listener name>

– Check that the INSTANCE_NAME parameter in the connect descriptor specifies an instance name known by the listener.

– Check for an event in the listener.log file.

ORA-12522: TNS:listener could not find available instance with given INSTANCE_ROLE
Cause: There are not any available and appropriate database instances registered with the listener, that are part of the service identified by SERVICE_NAME given in the connect descriptor and that have the specified INSTANCE_ROLE (and INSTANCE_NAME, if specified).
Action: Check to make sure that the INSTANCE_ROLE specified is correct. Run “lsnrctl services” to ensure that the instance(s) have registered with the listener and that they are ready to accept connections.

Above are list of Oracle Database Errors or Warnings from Error ORA-12511 to ORA-12522 received while performing certain operation against Oracle Database or related products.

What are Oracle Database Error Messages?

Oracle Error Messages may be returned while using products which are part of Oracle Database. Each Oracle Database Error or Warning Message mentioned above contains the Warning or Error Message Statement, a short explanation of the probable causes of the Error message, and a recommended action.

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